Method for recycling cans

ABSTRACT

A method and apparatus for recycling cans is disclosed. Discrimination of overweight conductive material from acceptable conductive materials from a mixed material input, while maintaining a high level of acceptable material recovery is achieved by control of the input to the separation system, as well as control of the separation mechanism.

This application is a continuation of application Ser. No. 459,827,filed Jan. 21, 1983 now abandoned.

BACKGROUND OF THE INVENTION

Recycling of used products for reclamation of raw materials has become away of life. Specifically, recycling of aluminum cans for reclamation ofthe aluminum is now commonplace.

Typically, a consumer saves a plurality of containers and brings thesecontainers to a mobile or permanent recycling facility, where thecontainers are turned over to an employee of the recycling company whoweighs or counts the containers and pays the consumer for the containersat a prestated rate. Unfortunately, such a system is labor intensive,requiring at least one operator to be at each facility whenever it isopen.

One possible solution to the labor problem is to replace many of themanned stations with automated facilities. This, however, results inother problems.

If the ideal were reached, i.e., a customer places only aluminum cansinto such a "reverse vending" machine, such a machine would be simple.All that would be necessary would be a means for weighing or countingthe cans, a payout apparatus linked to the weighing or counting meansand a means for storing the cans collected. However, such an ideal isnever realized.

First, all beverage containers are not aluminum. Thus, a reverse vendingmachine must be capable of distinguishing steel from aluminum, so thatno payment is made for steel cans.

While the placing of steel cans in a reverse vending machine designed toaccept aluminum cans could be inadvertent on the part of the consumer,other deliberate acts must also be overcome by such a machine. It is notunknown for unscrupulous consumers to place bottles, rocks, sticks andother debris into reverse vending machines. Thus, the machine must beable to separate aluminum cans from this debris, handle the debriswithout damage to the machine and pay only for the aluminum cans.Additionally, other consumers, looking to cheat the machine, will placesand, rocks, water, and other materials into aluminum cans, hoping to bepaid for the weight of the filled can. Or, a customer, not knowing thedamage that a relatively large solid block of aluminum can do to a cancrusher, may place portions of aluminum engine blocks, baseball bats andother massive aluminum materials into the reverse vending machine. Thus,in order to protect itself, as well as to avoid payment for weightedcans, the machine must be capable of discriminating between aluminumbodies based upon their weight.

Several means are known in the prior art for collecting aluminumcontainers. U.S. Pat. No. 4,179,018 uses air and magnetics as a means ofisolating aluminum cans from mixed trash. U.S. Pat. No. 4,062,767 uses alinear induction motor (LIM) to accomplish this result. Yet, each ofthese systems has shortcomings associated therewith. Thus, the airclassification system has trouble discriminating between various weightsand shapes of cans, sometimes paying for somewhat overweight cans andsometimes not paying for acceptable material. The known LIM systems donot significantly control the mixed trash input to the linear inductionmotor so that proper control of overweight materials, as well ascomplete collection of properly weighted cans, is accomplished.

Another deficiency in many of the known reverse vending machines is thenecessity, due to the layout and material flow of these machines, for aseparate storage for steel cans which are inadvertently collected by thesystem. Since this storage area is typically small with respect to thestorage area for aluminum cans, and since overflow of this small arearequires frequent servicing of the machine, such a system eithersignificantly increases servicing costs or significantly increases thesize of the machine to provide adequate steel can storage.

Other problems which may arise in the operation of a reverse vendingmachine include overloading of a can crusher due to a high density offlattened cans or axially crushed cans, commonly known as "hockeypucks", and conveying mechanisms for the input to the machine beingincapable of accepting the very last portions of input to the system.

It is thus a primary objective of the present invention to provide areverse vending machine which is capable of discriminating betweenvarious weights of aluminum products received, such that overweightmaterials are not paid for and assure that acceptable materials arereliably paid for. It is also an objective of the present invention toeliminate the necessity for a separate steel storage facility. It isalso a primary objective of the present invention to provide a reversevending machine which includes means for preventing overloading ofcrushing means within the mechanism when high density aluminum isreceived. It is also a primary objective of the present invention toprovide apparatus for insuring that all material received by themechanism is processed by the system.

THE PRESENT INVENTION

By means of the present invention, these desired objectives areobtained.

The reverse vending machine of the present invention includes a methodand apparatus for discriminating between acceptable weight aluminum cansand other materials. This includes controlling discharge from an inputconveyor belt such that a single layer of aluminum cans and accompanyingmaterials results at the output position of said belt at a given time,magnetically separating steel and other magnetic materials from thematerial input at the discharge of the input conveyor belt, positioninga conveyor to accept the discharge from the input conveyor belt,positioning a linear induction motor under the conveying surface of theoutput conveyor, controlling the speeds of the input and outputconveyors such that the entire material from a given discharge positionof the input conveyor has passed the discharge position of the inputconveyor prior to entry of the next material onto the output conveyor,and controlling the speed of the output conveyor and the electromotiveforce supplied by the linear induction motor to permit only aluminummaterials within a given weight range to be transported from the outputconveyor by the linear induction motor.

The method and apparatus of the present invention further includescontrolling of input to a can crusher forming a part of the system bycontrolling output from a weigh hopper feeding the crusher. This controlcomprises controlled opening and closing of a door positioned as thebottom floor of the weigh hopper in a controlled speed manner such thatthe crusher does not receive an overabundance of cans at one time.

The method and apparatus of the present invention also includesrecombining of the steel cans collected with stored aluminum cans priorto and/or after weighing of the aluminum cans and prior to and/or duringcrushing of the aluminum and steel cans. This is accomplished bydirectly feeding the steel cans removed by the input conveyor to the cancrusher, bypassing the weigh hopper. This results in both the aluminumand steel cans being transported to a single storage facility within thereverse vending machine, eliminating the necessity for a separate steelcollection capability.

The method and apparatus of the present invention also includes an inputhopper, input conveyor and input conveyor baffle mechanism which assuresthat all materials fed to the system by the customer will be conveyed bythe input conveyor. This is accomplished by means of a shield locatedbeneath the input conveyor and positioned such that cleats on theconveyor pull material from between the shield and the conveyor andthrough the system.

BRIEF DESCRIPTION OF THE DRAWINGS

The method and apparatus of the present invention will be more fullydescribed with reference to the drawings in which:

FIG. 1 is a perspective view of the reverse vending machine of thepresent invention, with the outer walls thereof in phantom;

FIG. 2 is a right side view with the outer walls in phantom;

FIG. 3 is a back view with the outer walls in phantom;

FIG. 4 is a top view with the storage bin removed;

FIG. 5 is a side elevational view, partially broken, of the inputconveyor mechanism;

FIG. 6 is a partial side elevational view of the input hopper and inputconveyor mechanism, with the side panels thereof removed;

FIG. 7 is a side elevational view illustrating the linear inductionmotor and its associated conveying mechanism;

FIG. 8 is a front elevational view of the weighing scale mechanism;

FIG. 9 is a side elevational view of the weighing scale mechanism;

FIG. 10 is a partial cross-sectional view illustrating the connectionbetween the door mechanism and the balance of the weigh scale mechanism;

FIG. 11 is a side elevational view of a typical uncrushed beverage can;

FIG. 12 is a side elevational view of a partically crushed beverage can;and

FIG. 13 is a side elevational view of a axially crushed can or "hockeypuck".

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to the FIGURES, and especially FIGS. 1 through 4, thepassage of material through the reverse vending machine of the presentinvention will be described. Upon arrival at the reverse vending machine1, a customer opens door 10 by sliding it from its closed position toits open position, as illustrated. The customer then dumps the materialto be handled by the machine 1 into entry hopper 14. Entry hopper 14 isprotected by shield 12, which is a grid formed from rods, bars and thelike. This shield 12 protects the machine 1 from inordinately largematerials, such as castings, extrusions, or the like. Clearly, however,the shield 12 cannot protect the machine 1 from every foreign objectwhich may be fed to the system. Thus, other protective mechanisms willbe described below.

After filling hopper 14 to its capacity, or having run out of materialto feed to the machine 1, the customer closes door 10 and pushes startbutton 2, beginning operation of the machine 1. A signal light 4 mayindicate beginning of operation of the system 1. Start button 2 andsignal light 4 are held within panel 5. An alphanumeric display box 6may update the customer as to the status of the operation throughout theprocessing. Thus, this box 6, which is microprocessor controlled, as isthe entire system, may indicate that the machine is ready for operation,is out of service, is processing the material, and may indicate theamount of payout to be made.

The material for processing is transferred from input hopper 14 by meansof input conveyor 16. A more detailed description of this operation willbe described below, with reference to FIGS. 5 and 6. Shield 13 (FIG. 6)captures any material which may fall back from conveyor 16, so that thismaterial is again caught up by the conveyor 16 for processing. At thedischarge end of conveyor 16, a magnetic head pulley 104 captures allmagnetic materials, such as steel cans, and other ferromagneticmaterials, causing these materials to be held onto belt 100 until belt100 passes from magnetic head pulley 104. This causes any magneticmaterials to fall into chute 19, where they are carried along chute 19and pass over a spring-mounted door 21. Spring-mounted door 21 isadjusted such that steel materials weighing somewhat more than steelcans will trip the door, thus causing these materials to fall into areceptacle. The balance of steel materials are then held by gatemechanism 23 until a signal is given to open gate mechanism 23 andpermit these materials to pass into crusher 38. It should be noted thatgate mechanism 23 may be eliminated, with the steel materials notpassing through door 21 then passing directly to crusher 38.

Non-magnetic materials exit belt 100 onto conveyor 18. These materialsare carried by conveyor belt 198 over a linear induction motor mechanism27, including a blower 30 for cooling and an enclosure 28 within which alinear induction motor 220 is mounted. Baffles 20 and 22 are positionedat the beginning of conveyor 18, to prevent materials exiting conveyorbelt 100 from falling from the system. Further, belt 198 is unsupportedalong its length corresponding to the width of conveyor 16. This alsoaids in preventing materials from bouncing off of conveyor 18.

As the material passes over linear induction motor 220, conductivematerials, such as aluminum cans, will be deflected by the linearinduction motor 220 into a weigh hopper 32. Non-conductive materials,such as paper, sticks and the like, as well as overweight conductivematerials, for reasons to be explained below, are not deflected bylinear induction motor 220 and pass off the end of conveyor 18 to becollected as waste.

Once all material has existed conveyor 18, the weight of hopper 32 andits contents is determined. Hopper 32 is mounted by means of rails 31and cross rails 33 to a scale mechanism 34, which is in turn hung fromthe ceiling of the machine 1 by means of rails 36. The weight of thematerial within hopper 32 is determined, with this signal being relayedto a microprocessor controlled coin vault 9, where the consumer is paidbased on a pre-determined amount per unit weight through pay out slot 8with the amount being displayed on alphanumeric display box 6.

The cans in weigh hopper 32 are then permitted to enter can crusher 38,by opening a bottom door on weigh hopper 32, in a manner which will bemore fully described below with respect to FIGS. 8, 9 and 10, the cansare crushed, and conveyed by means of blower 40 through chute 42 intostorage bin 44. As will readily be realized, both steel cans from chute19 and aluminum cans from weigh scale 32 are combined during thecrushing, blowing and storage operations.

This is in contrast to prior systems, where steel materials wereseparated and held separately. In the prior systems, storage facilitieswere necessary for the steel materials, and, due to the nature of suchsystems, this storage was small relative to that for aluminum cans.Unfortunately, the small steel storage necessitated service at morefrequent intervals than would be desired.

Cans collected by reverse vending machines are normally transported to apermanent recycling facility. At such facilities, magnetic separatorsare routinely employed to separate steel from aluminum, in the same waythey are separated for customers bringing cans directly to the center.Thus, isolation of steel at the reverse vending machine is unnecessary.The reverse vending machine 1 of the present invention recombines steeland aluminum cans in a single storage bin 44 on top of the reversevending machine 1, after having previously separated these materials forweighing of the aluminum cans.

As previously mentioned, the reverse vending machine 1 is microprocessorcontrolled. The various wiring and circuitry necessary to operate thesystem are contained within cabinets 50 and 52 and are conventional tothose of ordinary skill in the microprocessor field. An air conditioner54 is provided for cooling of the components.

Thus far, the general operation of the reverse vending machine 1 hasbeen described. A detailed consideration of various components isnecessary, however, in order to fully appreciate the interrelations andoptimizations present in the reverse vending machine 1 of the presentinvention.

FIGS. 5 and 6 illustrate the input conveyor assembly of the presentinvention. In FIG. 6, the input hopper 14 into which the customer placesthe material to be recycled, as previously described, is positionedadjacent to input conveyor 16 having a conveyor belt surface 100 and aplurality of cleats 125 extending therefrom. A baffle or shield 13 ispositioned at the bottom of hopper 14. This baffle 13 is concentric withpulley 110 around which belt 100 passes and comprises an arc having alength at least equal to the spacing between adjacent cleats 125. Whenlooking at FIG. 6, the necessity for the baffle 13 becomes evident. Asthe belt 100 is advanced, a cleat 125 proceeds from its initial position125b illustrated in solid lines, which prohibits material in hopper 14from advancing beyond cleat 125b, to its dotted line position 125a,which opens the bottom of hopper 14. As this occurs, another cleat 125advances from its initial position 125d in solid lines to its dottedline position 125c, sweeping material passing through the bottom ofhopper 14 and advancing this material for recovery.

Thus, it is clear that baffle 13 must have an arc length at least equalto the distance between adjacent cleats 125, to assure that no materialmay pass out of the system at this point. Of course, the length ofbaffle 136 may be somewhat longer than the minimum required.

This hopper-baffle-conveyor cleat arrangement replaces previously knownmechanisms which comprise a one-way door located at the bottom of aninput hopper, permitting belt cleats to rise, but prohibiting materialfrom passing downwardly through the door. Such a mechanism has beenfound inadequate with steeply inclining input conveyors, since the doorpushes back material toward the hopper and, it has been found that thelast-remaining material in the hopper was not always capable of beingcaptured by the conveyor mechanism 16, as it was consistently pushedback into hopper 14 by the door.

As previously mentioned, the necessity for the baffle mechanism was dueto the requirement of a steeply inclined input conveyor 16. Thisconveyor 16 may be positioned at an angle from about 55 to 75° , andpreferably at an angle of about 65° . This steep angle helps to assurethat a single level of material is carried by the cleats 125 of conveyor16, rather than having a plurality of cans piled upon one another, whichcould result from a shallow conveyor inclination, and which in the pasthas required belts, chains or other dragging mechanism to level the loadon input conveyor 16.

FIG. 5 more clearly illustrates the details of the input conveyor 16.The conveyor 16 comprises a belt 100 having a plurality of cleats 125along the length thereof. Belt 100 is positioned between a pair ofpulleys 102 and 104. Pulley 102 is adjustable by means of bracket 112,slide 114 attached to pulley 102 and positioned within bracket 112 andlocking bolt 116 and locking nut 118. Pulley 104 is a magnetic headpulley which maintains magnetic materials on belt 100 as they passaround pulley 104, to be dropped off into chute 19 (FIG. 1). Conveyormechanism 16 is driven by means of motor 15 and gear box 17 (FIG. 1) andbelts or chains (not shown) connecting gear box 17 to pulley 104. Guide130, which deflects belt 100 out of its normal path between pulleys 104and 102, helps position the magnetic materials for entry into chute 19.This direction of magnetic materials to chute 19 may, of course, beaccomplished by other means.

Belt 100 is preferably formed from a fabric or rubberized surface 120and rides over a slider bed 122. Cleats 125, comprising a base 127 andan outstanding foot 126 formed as a single piece, are attached to thefabric or rubberized surface 120 through an intermediary steel backing124. Alternatively, cleats 125 could be formed integrally with belt 100.

An important element of the conveyor 16 is the spacing of the cleats125. The cleats 125 are spaced a distance A between one another, withthis distance A being selected to permit a single row of metallic cansto be carried lengthwise between adjacent cleats 125. This length mayrange from about 6 to about 8 inches (15.24 to 20.32 centimeters) and ispreferably about 7 inches (17.78 centimeters). If the length A becomestoo short, containers may be pinched between adjacent cleats 125 as theypass over pulley 104, and thus fed to chute 19 or dropped onto the floorof the machine 1, rather than onto conveyor 18. On the other hand, ifthe spacing A between adjacent cleats 125 is too large, an over supplyof material for processing from each cleat 125 may result on belt 18,reducing the effectiveness of the material discrimination system.

The height B of the cleats 125 is also carefully selected. This heightmay range from about 1.5 to about 3.0 inches (3.81 to 7.62 centimeters)and is preferably about 2.0 inches (5.08 centimeters), so that metalliccontainers may be carried on their sidewalls by the conveyor 16, butwithout the containers being stacked upon one another verticallyoutwardly from the belt surface 100.

FIG. 7 illustrates the LIM separator mechanism employed in the presentinvention. A conveyor belt 18 is positioned between a pair of pulleys200 and 202. Pulley 200 is driven by means of motor 212, gear box 210and belt or chain 208. The tauntness of belt 18 is adjusted by means ofbracket 204, slide 203 and bolt 206 and nut 208, similar to theadjustments previously described for conveyor 16.

Belt 18 is unsupported along its length, except at its position abovelinear induction motor housing 28. Housing 28 contacts the belt 18,supporting belt 18 and the materials thereon as the belt 18 passesthereover.

Contained within housing 28 is a linear induction motor 220. This linearinduction motor 220 is selected to have sufficient power to change thedirection of movement of conductive materials, such as aluminum cans,from their direction of movement along belt 198 to a movement acrossbelt 198 and into weigh hopper 32 (FIG. 1). The motor must havesufficient power to move these materials whether they be in the form ofuncrushed cans 400, as illustrated FIG. 11, partially crushed cans 402,as shown in FIG. 12 or axially crushed cans in the form of "hockeypucks" 404 as illustrated in FIG. 13.

Linear induction motors are described with reference both to their powerrating and to their duty cycle. Due to the nature of these motors, muchheat is generated when in use. Thus, these motors cannot be usedcontinuously, but have a duty cycle, typically in the range of about25%. As illustrated in FIG. 7, a heat sink 222, comprising an aluminumfinned extrusion, and a cooling fan 30 are employed to increase theeffective duty cycle of linear induction motor 220. By employing theseelements, it is possible to increase the duty cycle of LIM 220 toapproximately 50%.

As previously mentioned, while linear induction motor 220 must transportaluminum containers into weigh hopper 32, linear induction motor 220must not permit exceptionally overweight containers to be accepted.There are numerous controls built into the system of the presentinvention to tune the system accordingly. Belt 198 is operated at aminimum speed sufficient to transport all material carried by a singlecleat 125 of input conveyor 16 past the discharge point of inputconveyor 16 prior to delivery to belt 198 of material from the nextcleat 125. The speed of belt 198, in conjunction with the power outputof linear induction motor 220 and the frictional characteristics of belt198, determines how quickly and the maximum weight of a piece ofmaterial which could be moved across belt 198 by linear induction motor220. By properly tuning the speed of input conveyor 16, conveyor 18 andthe power output of linear induction motor 220 and by properly selectingthe belt 198, the system may be fine tuned to accept containers aslittle as two times the weight of a typical empty aluminum container byrejecting materials over that weight, and maintain an almost 100%collection rate of containers within the prescribed weight range.

All materials which are not moved by linear induction motor 220 intoweigh hopper 32 pass over the edge of pully 202 and are collected withina waste container therebeneath.

The weighing mechanism employed in the reverse vending machine of thepresent invention is illustrated in FIGS. 8, 9 and 10. A weigh hopper 32is supported by means of rails 31 and 33 from a scale mechanism 34.Scale 34 is in turn hung from the roof of the reverse vending machine bymeans of rails 36. The weigh hopper 32 comprises a plurality of wallpanels 301, 303, 307 and 309 and a bottom door panel 300. As previouslyexplained, if the weigh hopper 32 contains a high density of compactedcans, such as the hockey pucks 404 illustrated in FIG. 13, emptying ofthe entire load filling weigh hopper 32 may overload crusher 38. Thus,door 300 is mounted for controlled opening as will now be described.

Door 300 is mounted by means of attachment plate 311 to a slidemechanism comprising of inner slide member 304 and an outer slide member302, similar to slides employed in furniture drawers. Also mounted toattachment plate 311 is a rack 306, which comprises a toothed rail.Pinion 308 mounted upon shaft 310 and connected to a gear motor 320rotates at a predetermined rate, when given a signal to do so by thecontrol mechanism of the reverse vending machine. The rotation of pinion308 moves rack 306, due to the toothed engagement therebetween, therebymoving door 300 along slide members 302 and 304.

The rate of opening and closing of door 300 can be controlled by varyingthe speed of the motor (not shown) driving pinion 308 and/or by theratio of teeth on the rack and pinion members 306 and 308. Typically,opening and closing rates of between about 30 and 50 inches per minute(76.2 and 127.0 centimeters per minute) and preferably about 40 inchesper minute (101.6 centimeters per minute) will enable the crusher 38 tooperate satisfactorily by preventing an overabundance of cans at crusher38.

As illustrated, the system 1 has weigh scale 32 directly above cancrusher 38. If, however, for whatever considerations it is necessary tooffset weigh scale 32 with respect to crusher 38, an elbow connectiontherebetween may be employed, and, if necessary, door 300 may be mountedas a bottom part of a sidewall of scale 32.

From the foregoing, it is clear that the method and apparatus of thepresent invention provides solutions to numerous problems which havebeen encountered in prior known reverse vending machines.

While the method and apparatus of the present invention have beendescribed with reference to certain specific embodiments thereof, it isnot intended to be so limited thereby, except as set forth in theaccompanying claims.

We claim:
 1. In a method for recycling conductive material from amaterial input comprising separating magnetic material from saidmaterial input and separating said conductive material from the balanceof said material input the improvement comprising separating overweightconductive material from said conductive material while maintaining anacceptable level of acceptable weight conductive material recovery bycontrolling the angle from the horizontal, the height of individualcleats and spacing of adjacent cleats of a cleated input conveyor suchthat not more than a single row of conductive material is input from agiven cleat, positioning an output conveyor perpendicular to and at theexit of said input conveyor and parallel to the axis of said cleats, andcontrolling the relative speeds of said input conveyor and said outputconveyor such that all of said material input from a given cleat of saidinput conveyor discharged onto said output conveyor passes the dischargepoint of said input conveyor in a direction perpendicular to itsdirection of movement along said input conveyor and parallel to the axisof said cleats prior to discharge of said material input from the nextof said cleats, thereby controlling the amount of said material input tobe separated in a given period of time and controlling the speed andfrictional characteristics of said output conveyor and the power inputto a linear induction motor positioned beneath said output conveyor,thereby controlling said separating of said conductive material from thebalance of said material input.
 2. The method of claim 1 wherein saidangle ranges between about 55° and 75°.
 3. The method of claim 2 whereinsaid angle is about 65°.
 4. The method of claim 1 wherein said cleatheight ranges between about 1.5 and 3.0 inches (3.81 and 7.62centimeters).
 5. The method of claim 4 wherein said cleat height isabout 2.0 inches (5.08 centimeters).
 6. The method of claim 1 whereinsaid cleat spacing ranges between about 6.0 and 8.0 inches (15.24 and20.32 centimeters).
 7. The method of claim 6 wherein said cleat spacingis about 7.0 inches (17.78 centimeters).